Gravite Verilerine Spektral Filtreleme ve Lokal Optimizasyon-Tabanlı Ters Çözüm Teknikleri Uygulayarak Isparta Baseninde Temel Kaya Topografyasının Tahmini / Estimation of Basement Relief in the Isparta Basin by Applying Spectral Filtering and Local Optimisation-Based Inversion Techniques to Gravity Data

Öz

Isparta Havzası, Batı Anadolu genişleme bölgesi ile Toros orojenik kuşağının birleşim noktasında yer alan tektonik olarak karmaşık bir çöküntü alanıdır. Helen ve Kıbrıs yaylarının kesişimine yakın konumuyla Isparta Açısını oluşturmaktadır. Bu geçiş zonu, yoğun kabuksal deformasyon, karmaşık fay sistemleri ve aktif sismisite ile karakterize edilmekte olup, jeofiziksel araştırmalar açısından önemli bir çalışma sahasıdır. Bu kendine özgü tektonik ortamda sedimanter dolgu kalınlığını belirlemek amacıyla mikrogravite anomalileri analiz edilmiştir. Gravite verileri, 2-B Fourier dönüşümüne dayalı bir yöntem kullanılarak bölgesel ve rezidüel bileşenlerine ayrıştırılmıştır. Bu spektral filtreleme aşaması, yüzeye yakın sinyalleri daha geniş tektonik etkilerden etkin bir şekilde ayırarak, genellikle daha derin yapılar tarafından maskelenen sığ özelliklerin çözünürlüğünü artırmış ve derinlik modellemesi için sağlam bir temel oluşturmuştur. Rezidüel gravite anomalileri, hem 2-B hem de 3-B lokal optimizasyon-tabanlı ters çözüm teknikleriyle incelenmiştir. Bu tamamlayıcı yöntemler, sonuçların matematiksel olarak doğrulanmasına olanak tanımış ve elde edilen yapısal yorumların güvenilirliğini arttırmıştır. Elde edilen temel kaya derinliği tahminleri, Isparta Havzası’nın bilinen jeolojik yapısıyla, özellikle fay geometrileri ve stratigrafik sınırlarla uyum göstermektedir ve ters çözüm sonuçları maksimum sedimanter dolgu kalınlığının yaklaşık 0,53 km olduğunu göstermektedir. Tahmin edilen sedimanter dolgu kalınlığı, afet yönetimi açısından pratik önem taşımaktadır. Özellikle havza ortamlarında, kalın sedimanter birikimler deprem sırasında yer hareketi özelliklerini önemli ölçüde etkileyebilir. Bu nedenle, sedimanter birikimin uzamsal dağılımının haritalandırılması, daha bilinçli bölgesel risk değerlendirmelerine katkıda bulunmakta ve hedefli azaltma stratejilerinin geliştirilmesini desteklemektedir. Bu bulguların, Isparta Havzası'nda arazi kullanım planlaması ve altyapı dayanıklılığı için değerli çıktılar oluşturacağı ve sismik tehlike azaltma çalışmalarına katılan yetkililer ve mühendisler için temel bilgi kaynağı sağlayacağı öngörülmektedir.

Anahtar Kelimeler

• Isparta baseni
• spektral filtreleme
• temel kaya topografyası
• ters çözüm
• mikrogravite

Estimation of Basement Relief in the Isparta Basin by Applying Spectral Filtering and Local Optimisation-Based Inversion Techniques to Gravity Data

Öz

The Isparta Basin is a tectonically complex depression situated at the junction between the Western Anatolian extensional province and the Tauride orogenic belt. It lies near the intersection of the Hellenic and Cyprus arcs, forming the Isparta Angle. This transitional zone is characterised by intense crustal deformation, complex fault systems, and active seismicity, making it a key area for geophysical investigation. Microgravity anomalies were analysed to assess the thickness of the basin’s sedimentary deposits. A 2-D Fourier transformation-based procedure was used to decompose the gravity data into regional and residual components. This spectral filtering step isolated shallow subsurface signals from broader tectonic influences, thereby providing a robust foundation for depth modelling by enhancing the resolution of near-surface features that are often masked by deeper structural trends. Residual gravity anomalies were further examined using both 2-D and 3-D local optimisation-based inversion techniques. These complementary methods allowed for cross-validation of results mathematically and improved confidence in the derived structural interpretations. The resulting basement depth estimates demonstrate consistency and align well with the established geological framework of the Isparta Basin, including known fault geometries and stratigraphic boundaries, with the inversion results indicating maximum sedimentary fill thickness of approximately 0.53 km. This result has practical implications for disaster management, particularly in assessing the potential for seismic amplification. Thick sedimentary sequences can substantially affect ground-motion characteristics during earthquakes, especially within basin environments. Therefore, mapping the spatial distribution of sedimentary accumulation contributes to more informed regional risk assessments and supports the development of targeted mitigation strategies. These findings are expected to provide valuable input for land-use planning and infrastructure resilience in the Isparta Basin, offering essential baseline information for authorities and engineers involved in seismic hazard mitigation.

Anahtar Kelimeler

• Isparta basin
• basement relief
• inversion
• microgravity
• spectral filtering

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